Armchair with back insert



FIG. 1 is a front perspective view of an armchair with back insert showing my new design;

FIG. 2 is a front perspective view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a rear view thereof;

FIG. 6 is a bottom plan view thereof; and,

FIG. 7 is a left side view thereof. 

The ornamental design for an armchair with back insert, as shown and described. 